Emotions manage our behaviour and mood during survival-salient events and pleasurable interactions.

“Measuring a person’s emotional state is one of the most vexing problems in affective science.” (Mauss and Robinson. Measures of emotion: a review. Cogn Emot 2009;23:209–237). Although there is no reference standard measure of emotion, mood and feelings manage our behaviour and diet during daily life activities and important events.
Our body reacts in a different way to several emotions.